When re-opening a document with a rich text content block during login the CMS UI no longer responds

The demo is used to reproduce the issue. It is not yet clear if this a issue in the demo project or in the plugin itself. If it is specific to the demo environment priority can be lowered

Steps to reproduce:
1) Build content blocks demo [1]
2) Login as admin/admin
3) Create a new document and add a rte field
4) Save & Close the document
(Expected: Publication menu is available. Actual: Menu only shows an exclamation mark)
5) Open the document
6) Logout
7) Login again
Expected: Working CMS
Actual: Tab with the open document is shown, CMS is unresponsive. It is impossible to click on any element

Shown in the browser-console:
ReferenceError: Hippo is not defined CKEditorPanel-ver-1403081522000.js:6
TypeError: Hippo.createCKEditor is not a function cms:212

Reproduced on the demo with both 7.9.0 and 7.9.1-SNAPSHOT as parent version

[1] https://forge.onehippo.org/svn/content-blocks/demo/trunk